Skid top lifter

ABSTRACT

A lifting apparatus for handling skids includes a pair of grippers equipped with bite-arrays for penetrating into the skid runners. A pick-up module is supported from a hoist suspension providing controlled vertical movement thereof and mounts the grippers for oppositely directed translational movement. Spacer structure engages the skid to position the spikes of the bite arrays for unimpeded movement in a plane that intersects the skid runners. Fluid pressure drive mechanism actuates the grippers individually to produce separate movement thereof and applies self-balancing forces thereto to drive the grippers through runner-penetrating travel only after both grippers have established runner contacting engagement.

Busam [4 1 Apr. 25, 1972 [54] SKID TOP LIFTER Primary Examiner-Evon C. Blunk i Assistant Examiner-Johnny D. Cherry [72] Inventor. I Donald H. Busam, Hometown, Ill. Anomey wimam P. Pmcem [73] Assignee: lnterlake Steel Corporation, Chicago, Ill. 22 Filed: Feb. 19, 1970 Y [57] ABSTRACT I A lifting apparatus for handling skids includes a pair of grip- [211 App!" 124523 pers equipped with bite-arrays for penetrating into the skid runners. A pick-up module is supported from a hoist suspen- Cl---. 214/147 294/67 R sion providing controlled vertical movement thereof and m ounts the for oppositely directed translational Of Search 88, ovement spaccr structure engages the to pgsition the 214/654 731 spikes of the bite arrays for unimpeded movement in a plane that intersects the skid runners. Fluid pressure drive [56] References q mechanism actuates the grippers individually to produce UNITED STATES PATENTS separate movement thereof and applies self-balancing forces 1 thereto to drive the grippers through runner-penetrating travel 3,1 Hammond only after grippers have established runner contacting 3,420,564 1/1969 Jensen ..294/67 engagemem 3,241,695 3/1966 Bishop... ..2l4/l47 5 Claims, 6 Drawing'Figures SKID TOP LIFTER BACKGROUND OF THE INVENTION A need exists for versatile mechanical means for handling skids of various sizes and configurations to reduce the number of man hours devoted to manual handling of skids in production line operations. For example, in paper mill operations large stacks of paper are sandwiched between top and bottom skids in preparation for strapping the skids together so that the load of paper is secure for storage and shipment. Prior to the actual strapping operation, a protective shroud is applied to the paper. This requires that the top skid be elevated while the shroud is applied and then re-seated atop the paper stack, a procedure that has required the use of two men.

Although numerous clamping and elevating mechanisms are known to the art, no satisfactory device affords the versatility required for handling skids.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a lifting apparatus for handling skids of various sizes and con- The lifting apparatus of the invention includes a suspension for providing a controlled vertical movement. A pick-up module is carried by the suspension with its underside facing toward the skid to'be handled. The pick-up module includes guide structure mounting a pair of gripper mechanisms for oppositely directed translational movement, the gripper mechanisms having bite means for penetrating into the skid runners. The lifting apparatus includes spacer structure engageable with the skid for positioning the bite means of the gripper mechanisms for movement in a plane that intersects the runners. Fluid pressure driving mechanism actuates the gripper mechanisms individually to produce separate movement thereof, the drivingmechanism being operable to apply self-balancing actuating forces to drive the gripper mechanisms through runner-penetrating travel only after both gripper mechanisms have established runner contacting engagement.

Because each of the gripper mechanisms are supported for independent movement, the lifting apparatus need not be positioned symmetrically with respect to the skid runners.

Yet, secure runner-penetrating travel 'of the gripper mechanisms is obtainable by the action of the self-balancing operating forces applied by the driving mechanism.

Other features and advantages of the invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which show structure embodying preferred features of the present invention and the principles thereof, and what is now considered to be the best mode in which to apply these principles.

' BRIEF DESCRIPTION OF THE DRAWINGS FIG. is a perspective view showing the two L-shaped carriage sub-assemblies; and

FIG. 6 is a diagramatic illustration of the fluid pressure drive mechanism of the lifter of FIG. 1.

Turning now to the drawings, a typical skid load 10 is shown as including a stack of paper 11. sandwiched between a top skid l2 and a bottom skid 13. In the case of a skid load of paper, it is the practice to lift the top skid 12 off the load and apply a protective shroud to the stack of paper and then replace the top skid 12.

The present invention provides lifting apparatus for mechanizing the handling of the top skid. The lifting apparatus includes a pick-up module M for engaging the top skid 12 and a suspension S connected to the pick-up module M for raising and lowering the same. The suspension is shown to include a lift ring 18 attached to the pick-up module M and'a hoist 19 supported on a trolley 20 that runs along a track 22. The hoist 18. A power cord 23 for the hoist 19 is shown connected to a control unit C on a pick-up module M. Conventional hoist control circuitry is incorporated in the control unit C to enable the operator to impart controlled vertical movement to the pick-up module while simultaneously manually guiding the landing of the pick-up module in suitable position upon the top skid 12. I

For purposes of disclosure, it may be noted that the top skids typically have a substantially flat load bearing section or main body 16 and a plurality of runners 17 attached in spaced parallel relation upon the load-bearing section 16. The runners have side faces 17F that are intersected by a common plane.

As is explained in greater detail hereinafter, the pick-up module includes support, guiding and driving facilities for controlling a pair of bite-arrays B to impart oppositely having a bottom wall 278 and integral end walls 27E. As best directed translational movement to such arrays in the plane that intersects the runner side faces 17F. The module also includes fluid pressure driving mechanism D for actuating the bite-arrays B to produce separate movement thereof. The driving mechanism D includes means to apply self-balancing forces to power the bite-arrays B through runner penetrating travel after both bite-arrays have established runner'contacting engagement.

The main frame of the pick-up module comprises an inverted U-shaped cover 24 having a top wall 24T and integral sides 245 connected by a pair of internal inverted U-shaped rib sections 25, 26 and a mating generally U-shaped base 27 shown in FIG. 5, the gripper-mechanisms comprise a pair of mating L-shaped sub-assemblies 28, 30 which slidably interengage to define a generally rectangularly shaped composite carriage structure that is expansible and retractable. More specifically, sub-assembly-28 comprises an elongated shaft 32 having a cantilever plate 34 rigid with and projecting transversely from one end thereof. A bearing plate 36 having a guide hole 38 is rigidly carried at the free end of cantilever plate 34. Similarly, sub-assembly 30 includes an elongated shaft 40, a cantilever plate 42 and a bearing plate 44 having a guide hole 46. Each of the plates 34, 42 rigidly mount the bite means B for penetrating the skid runners. Each bite means B of this embodiment comprises a pair of spike assemblies.

As shown in FIGS. 2 and 3, shafts 32 and 40 of sub-assemblies 28, 30 are slidably joumalled in aligned guide holes pro-' vided in rib sections 25, 26 of the main frame. The bearing plate 36 of sub-assembly 28 also journals the shaft 40 of sub-' assembly 30 while bearing plate 44 of sub-assembly 30 journals the shaft 32 of sub-assembly 28. Thus the gripper mechanisms comprising sub-assemblies 28, 30 are freely moveable in translation in either direction independently of one another.

Each spike assembly is identical and as best shown in FIG. 4, each comprises a rectangularly shaped top carrier plate 52 covering a pair'of side plates 53, 54 welded to opposite ends thereof. Each of the side plates 53, 54 extend below the plane of the top carrier plate 52 sufficiently to enable the engagement of suitably threaded spikes 55 into corresponding tapped holes provided in lengthwise spaced relation along each of plates 53, 54. Screws 56 secure each top plate 52 to a depending strut 525 which is welded to the corresponding cantilever plate. The struts 52S operate in lengthwise clearance slots 278 in the base 27.

Spacer structure comprising a pair of spaced-apart integral extensions 24E on each of the cover side walls 248 position the gripper mechanisms so that the spikes 55 are movable in a plane P (see FIG. 4) that is spaced from the load bearing section 16 and intersects the runners 17.

The fluid pressure drive mechanism is connected to the gripper mechanisms to produce separate movement thereof. In the illustrated embodiment, the drive mechanism is shown being of a single-ended pneumatic type which is mounted between and supported by the cantilever plates of the carriage and includes a cylinder 57 and a piston rod unit 58. The cylinder has a fork 57F at its closed end connected by a pivot pin 57? to carriage plate 42. The piston rod has a fork 58F on its free end connected by a pivot pin 58F to the carriage plate 34.

The pneumatic control system for the drive mechanism includes an inlet flow control valve 60, a pressure regulator 61, a pressure gauge 62, a manual valve 63 and a muffler 64 all mounted on the side walls 248 of the cover (see FIG. 2) and interconnected by suitable airlines L (see FIG. 6). Additional air lines 65, 66 are shown connected to ports at opposite ends of the cylinder to allow the setting of the manual valve to effect expansion or retraction of the drive mechanism and the gripper mechanism.

The control unit C is shown secured to the cover side wall 248 that carries the manual valve 63. The control unit includes a duct 67 supporting a control housing 68 that is provided with hand bars 69. The duct serves as a slide track for a valve actuator rod 70 which includes a control handle 71 projecting from wall slots provided in the duct. The housing 68 mounts a selector switch 72 having push buttons 73 connected to a power receptacle 74 that is mounted on the duct for plugconnection to the power cord 23.

As is by now apparent, operation of the lifter is greatly facilitated by the convenient relative location of the manual control bars 69, hoist control switch 72, and fluid pressure drive control 71. Specifically, the extension of the control group from the pick-up module serves two purposes: (1) to position the control group outboard of the skid top itself (see FIG. 1), and (2) it provides for increased leverage so that the skid top is easy to control, even if it is gripped a good distance from its front to back mid-point. Additionally, the control arrangement facilitates one-hand operation (with either hand). In operation, the operator manually shifts the lifter by means of the hand bars 69 along the track 22 to a position above a skid load 10 and lowers the module M by actuating the push button switch 72. As stated above, the skids 12 differ in size so that the spacing of the runners 17 can vary widely. Successful operation of the lifter of the present invention, however, is not limited by such variations. If, for example, the runners are extremely widely spaced, the operator can guide the module so as to seat upon the skid straddling a single runner (as depicted in F IG. 1). In such a case, the fluid pressure drive mechanism is actuated so as to cause the air cylinder 57 to undergo a compression stroke, thereby moving the bite-arrays B inwardly toward the two opposite side faces 17F of the runner 17.

It will be noted that because each of the gripper sub-assemblies 28, 30 are free to move independently of each other, the driving forces applied by the air cylinder 57 are self-balanced so that the bite-arrays B are powered through runner penetrating travel only after both bite-arrays have established runner contacting engagement.

F IG. 4 depicts a situation wherein adjacent runners are gripped by causing the fluid pressure drive mechanism to undergo an expansion stroke.

Thus, while preferred constructional features of the invention are embodied in the structure illustrated herein, it is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of up-raised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid to grip the same and to be raised for picking-up the skid, said pick-up module including a cooperating pair of gripper mechanisms each having bite means for engagement with the skid runners, a main frame having guide structure mounting the gripper mechanisms for independent oppositely directed rectilinear translational movement, driving mechanism for actuating said gripper mechanisms and including a cylinder mounted to one of said gripper mechanisms and having a cylinder rod connected to the other of said gripper mechanisms, and means for producing relative movement of said cylinder and said cylinder rod to apply balanced actuating forces to said gripper mechanisms to drive said gripper mechanisms rectilinearly to runner penetrating travel after both bite means have established runner contacting engagement, each gripper mechanism is an L-shaped structure comprised of an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation to constitute a generally rectangular composite carriage that is expansible and retractable.

2. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of up-raised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid to grip the same and to be raised for picking-up the skid, said pick-up module including a cooperating pair of gripper mechanisms each having bite means for engagement with the skid runners, a main frame having guide structure mounting the gripper mechanisms for independent oppositely directed rectilinear translational movement, driving mechanism for actuating said gripper mechanisms and including a cylinder mounted to one of said gripper mechanisms and having a cylinder rod connected to the other of said gripper mechanisms, and means for producing relative movement of said cylinder and said cylinder rod to apply balanced actuating forces to said gripper mechanisms to drive said gripper mechanisms rectilinearly to runner penetrating travel after both bite means have established runner contacting engagement, each gripper mechanism is an L-shaped structure comprised of an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation to constitute a generally rectangular composite carriage that is expansible and retractable, the cantilever plate of one gripper mechanism is connected with said cylinder and the cantilever plate of the other gripper mechanism is connected with the said cylinder rod to carry said cylinder and said cylinder rod as a part of said composite carriage.

3. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurarity of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid, grip the same, and to be raised for picking-up the skid; said pick-up module including a pair of mating generally L-shaped gripper mechanisms slidably interengaged to define a generally rectangularly shaped expansible and retractable composite carriage structure, separate bite means carried by each of said gripper mechanisms for clamping engagement with the skid runner, a main frame mounting said carriage structure and engageable with said skid to position the bite means of said gripper mechanisms in a plane that intersects the runners, and fluid pressure driving mechanism including a cylinder having a cylinder rod mounted between said gripper mechanisms for selectively expanding and retracting said carriage structure to thereby drive said bite means into runner clamping contact, wherein said gripper mechanisms each comprise an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation.

4. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid, grip the same, and to be raised for picking-up the skid; said pick-up module including a pair of mating generally Lshaped gripper mechanisms slidably interengaged to define a generally rectangularly shaped expansible and retractable composite carriage structure, separate bite means carried by each of said gripper mechanisms for clamping engagement with the skid runner, a main frame mounting said carriage structure and engageable with said skid to position the bite means of said gripper mechanisms in a plane that intersects the runners, and fluid pressure driving mechanism including a cylinder having a cylinder rod mounted between said gripper mechanisms for selectively expanding and retracting said carriage structure to thereby drive said bite means into runner clamping contact, said gripper mechanisms each comprise an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper 6 mechanism in ,aptive relation, thecantilever plate .of one gripper mechanismis connected with said cylinder and the cantilever plateof-the'pther gripper mechanism is connected with said cylinder rod to carry said cy'lindei-and said cylinder rod as part of said composite carriage.

5. ln a lifting'appa'ratus for handling a skid of the type having a substantially flat load bearing section and a plurality of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid, gripthe same, and to be raised for picking-up the skid; said pick-up module including a pair of mating, generally L-shaped gripper mechanisms slidably interengaged to define a generally rectangularly shaped expansible and retractable composite carriage structure, separate bite means carried by each' of said gripper mechanisms for clamping engagement with the skid runner, a main frame mounting said carriage structure and engageable with said skid to position the bite 'means of said gripper mechanism in a plane that intersects the runners, and fluid pressure driving, mechanism including a cylinder having a cylinder rod mounted between said gripper mechanisms for selectively expanding and retracting said carriage structure to thereby drive said bite means into runner clamping contact, said gripper mechanism each comprise an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft' of the other gripper mechanism in captive relation, said main frame comprises a generally inverted U-shaped cover having a top wall and a pair of side walls, said side walls having inboard guide structure for receiving and guiding the elongated shaft of said gripper mechanisms. 1

lit 8' l. 

1. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid to grip the same and to be raised for picking-up the skid, said pick-up module including a cooperating pair of gripper mechanisms each having bite means for engagement with the skid runners, a main frame having guide structure mounting the gripper mechanisms for independent oppositely directed rectilinear translational movement, driving mechanism for actuating said gripper mechanisms and including a cylinder mounted to one of said gripper mechanisms and having a cylinder rod connected to the other of said gripper mechanisms, and means for producing relative movement of said cylinder and said cylinder rod to apply balanced actuating forces to said gripper mechanisms to drive said gripper mechanisms rectilinearly to runner penetrating travel after both bite means have established runner contacting engagement, each gripper mechanism is an Lshaped structure comprised of an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation to constitute a generally rectangular composite carriage that is expansible and retractable.
 2. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of up-raised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid to grip the same and to be raised for picking-up the skid, said pick-up module including a cooperating pair of gripper mechanisms each having bite means for engagement with the skid runners, a main frame having guide structure mounting the gripper mechanisms for independent oppositely directed rectilinear translational movement, driving mechanism for actuating said gripper mechanisms and including a cylinder mounted to one of said gripper mechanisms and having a cylinder rod connected to the other of said gripper mechanisms, and means for producing relative movement of said cylinder and said cylinder rod to apply balanced actuating forces to said gripper mechanisms to drive said gripper mechanisms rectilinearly to runner penetrating travel after both bite means have established runner contacting engagemeNt, each gripper mechanism is an L-shaped structure comprised of an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation to constitute a generally rectangular composite carriage that is expansible and retractable, the cantilever plate of one gripper mechanism is connected with said cylinder and the cantilever plate of the other gripper mechanism is connected with the said cylinder rod to carry said cylinder and said cylinder rod as a part of said composite carriage.
 3. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurarity of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid, grip the same, and to be raised for picking-up the skid; said pick-up module including a pair of mating generally L-shaped gripper mechanisms slidably interengaged to define a generally rectangularly shaped expansible and retractable composite carriage structure, separate bite means carried by each of said gripper mechanisms for clamping engagement with the skid runner, a main frame mounting said carriage structure and engageable with said skid to position the bite means of said gripper mechanisms in a plane that intersects the runners, and fluid pressure driving mechanism including a cylinder having a cylinder rod mounted between said gripper mechanisms for selectively expanding and retracting said carriage structure to thereby drive said bite means into runner clamping contact, wherein said gripper mechanisms each comprise an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation.
 4. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up module to be lowered onto the skid, grip the same, and to be raised for picking-up the skid; said pick-up module including a pair of mating generally L-shaped gripper mechanisms slidably interengaged to define a generally rectangularly shaped expansible and retractable composite carriage structure, separate bite means carried by each of said gripper mechanisms for clamping engagement with the skid runner, a main frame mounting said carriage structure and engageable with said skid to position the bite means of said gripper mechanisms in a plane that intersects the runners, and fluid pressure driving mechanism including a cylinder having a cylinder rod mounted between said gripper mechanisms for selectively expanding and retracting said carriage structure to thereby drive said bite means into runner clamping contact, said gripper mechanisms each comprise an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation, the cantilever plate of one gripper mechanism is connected with said cylinder and the cantilever plate of the other gripper mechanism is connected with said cylinder rod to carry said cylinder and said cylinder rod as part of said composite carriage.
 5. In a lifting apparatus for handling a skid of the type having a substantially flat load bearing section and a plurality of upraised runners in spaced parallel interconnected relation to the load bearing section, said apparatus including a pick-up moDule to be lowered onto the skid, grip the same, and to be raised for picking-up the skid; said pick-up module including a pair of mating generally L-shaped gripper mechanisms slidably interengaged to define a generally rectangularly shaped expansible and retractable composite carriage structure, separate bite means carried by each of said gripper mechanisms for clamping engagement with the skid runner, a main frame mounting said carriage structure and engageable with said skid to position the bite means of said gripper mechanism in a plane that intersects the runners, and fluid pressure driving mechanism including a cylinder having a cylinder rod mounted between said gripper mechanisms for selectively expanding and retracting said carriage structure to thereby drive said bite means into runner clamping contact, said gripper mechanism each comprise an elongated shaft having a cantilever plate projecting transversely from one end thereof and carrying the corresponding bite means, each cantilever plate terminating in guide structure for slidably receiving and guiding the elongated shaft of the other gripper mechanism in captive relation, said main frame comprises a generally inverted U-shaped cover having a top wall and a pair of side walls, said side walls having inboard guide structure for receiving and guiding the elongated shaft of said gripper mechanisms. 